/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.objcoding.calcite.csv.translate;

import org.apache.calcite.DataContext;
import org.apache.calcite.linq4j.AbstractEnumerable;
import org.apache.calcite.linq4j.Enumerable;
import org.apache.calcite.linq4j.Enumerator;
import org.apache.calcite.linq4j.QueryProvider;
import org.apache.calcite.linq4j.Queryable;
import org.apache.calcite.linq4j.tree.Expression;
import org.apache.calcite.plan.RelOptTable;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.type.RelProtoDataType;
import org.apache.calcite.schema.QueryableTable;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.Schemas;
import org.apache.calcite.schema.TranslatableTable;
import org.apache.calcite.util.Source;

import java.lang.reflect.Type;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Table based on a CSV file.
 */
public class CsvTranslatableTable extends CsvTable
    implements QueryableTable, TranslatableTable {
    /**
     * Creates a CsvTable.
     */
    CsvTranslatableTable(Source source, RelProtoDataType protoRowType) {
        super(source, protoRowType);
    }

    public String toString() {
        return "CsvTranslatableTable";
    }

    /**
     * Returns an enumerable over a given projection of the fields.
     *
     * <p>Called from generated code.
     */
    public Enumerable<Object> project(final DataContext root,
                                      final int[] fields) {
        final AtomicBoolean cancelFlag = DataContext.Variable.CANCEL_FLAG.get(root);
        return new AbstractEnumerable<Object>() {
            public Enumerator<Object> enumerator() {
                return new CsvEnumerator<>(
                    source,
                    cancelFlag,
                    getFieldTypes(root.getTypeFactory()),
                    fields);
            }
        };
    }

    public Expression getExpression(SchemaPlus schema, String tableName,
                                    Class clazz) {
        return Schemas.tableExpression(schema, getElementType(), tableName, clazz);
    }

    public Type getElementType() {
        return Object[].class;
    }

    public <T> Queryable<T> asQueryable(QueryProvider queryProvider,
                                        SchemaPlus schema, String tableName) {
        throw new UnsupportedOperationException();
    }

    public RelNode toRel(
        RelOptTable.ToRelContext context,
        RelOptTable relOptTable) {
        // Request all fields.
        final int fieldCount = relOptTable.getRowType().getFieldCount();
        final int[] fields = CsvEnumerator.identityList(fieldCount);
        return new CsvTableScan(context.getCluster(), relOptTable, this, fields);
    }
}
